Yo, My Magic launcher always has a problem with forge. I plays only SP (setup -> Test). When i open the window with Setup, I add the Forge (minecraftforge-universal-1.4.6-6.5.0.471.zip) and I see Fcukin "1 Error". Log is there (before start):
after start ("Mojang" and black screen)
Forge log
P.S: I have clean 1.4.6